海底沉积物生物气演化特征及气源影响因素分析  

Evolution characteristics of biogas in seabed sediments and their influencing factors on gas sources

作　　者：刘煜 李清[4] 林小云[1,2,3] 孔赟 肖七林[1,2,5] LIU Yu;LI Qing;LIN Xiaoyun;KONG Yun;XIAO Qilin(Hubei Collaborative Innovation Center for Unconventional Oil/Gas,Yangtze University,Wuhan 430100,China;Key Laboratory of Oil and Gas Resources&Exploration Technologies,Yangtze University,Ministry of Education,Wuhan 430100,China;College of Geosciences,Yangtze University,Wuhan 430100,China;Qingdao Institute of Marine Geology,China Geological Survey,Qingdao 266071,China;College of Resources and Environment,Yangtze University,Wuhan 430100,China)

机构地区：[1]长江大学非常规油气湖北省协同创新中心,武汉430100 [2]长江大学油气资源与勘探技术教育部重点实验室,武汉430100 [3]长江大学地球科学学院,武汉430100 [4]中国地质调查局青岛海洋地质研究所,青岛266071 [5]长江大学资源与环境学院,武汉430100

出　　处：《海洋地质与第四纪地质》2020年第6期169-177,共9页Marine Geology & Quaternary Geology

基　　金：国家重点研发计划“冷泉系统发育的地质条件及控制作用”(2018YFC0310001);国家自然科学基金“冲绳海槽中部高硫化氢背景下底栖有孔虫群落与壳体同位素特征”(41306062);山东省自然科学基金“冲绳海槽北部泥火山地球物理定量表征及其活动控制因素分析”(ZR201807100270)。

摘　　要：为研究海洋天然气水合物生物气源的影响因素及演化模式,选择了某海域3个海底沉积物样品进行微生物演化模拟实验。通过改变生气条件,分析不同温度、pH、碳源、碳源浓度、氮源和地层盐度对海底沉积物产甲烷菌生物气生成的影响。实验结果表明:某海域产甲烷菌在55℃时CH4产气量最高;pH为6~8时CH4产气量较高,且pH为10时仍有CH4产出;加入氮源、碳源都有一定程度的促进作用,但过高的碳源浓度会抑制CH4产气量;地层盐度的变化对CH4产气量影响不明显。根据不同温度微生物演化及产气率可将生物气演化分早期、高峰期和晚期3个阶段;pH为6~8、碳源选取乳糖(双糖)且浓度2.0 mL/L以及蛋白质为主要氮源时明显促进产甲烷菌产气率;按照采样点海域地温梯度及环境条件,认为采样点所在海域海底生物气源岩埋藏深度大约为200~500 m,具有弱碱性、弱径流水动力条件的地区可以作为重点勘查地区。In order to seek for the influencing factors on the biogenic gas sources in marine natural gas hydrate deposits and its genetic model,three marine sediment samples were collected for microbial evolution experiment.Various biogas production conditions,such as temperatures,pH,carbon source,carbon source concentration,nitrogen source,and formation salinity are changed to look for their effects on the biogas production by methanogenic bacteria in seabed sediments.The experimental results suggest that the methanogenic bacteria reach the highest methane production rate when temperature is at 55℃.The production remains high when pH changes between 6~8,and there is still methane gas produced until pH increased to 10.Both the nitrogen or carbon have certain degrees of promoting effect.However,carbon source concentration will inhibit methane gas production if it is too high.Change of formation salinity have no significant effect on methane gas production as the experiment indicates.According to the microbial evolution and gas production rate at different temperatures,biogas evolution can be divided into three stages:early stage,peak stage and late stage.When pH is between 6~8,and lactose(disaccharide)in concentration of 2.0 ml/L is selected as carbon source,and protein selected as the main nitrogen source,the biogas production rate of methanogens is significantly enhanced.Based on the geothermal gradient and environmental conditions of the sampling area,it is inferred that the major biogenic gas source rock is buried in a depth of about 200~500 m,and the area with weak alkalinity and weak runoff is the most favorable exploration target.

关 键 词：产甲烷菌 产气潜力 生物气 模拟演化实验 海底沉积物 

分 类 号：P736.4[天文地球—海洋地质]